The present invention relates to a composition and a process for constructing electronic devices wherein a substrate is coated with a conducting layer that is further coated with a thick film paste. The thick film paste may contain materials such as glass frit, various conductors, photo-imageable polymers and, usually a solvent. In the fabrication of these devices, photo-definable protective layers may be used to isolate photoimageable thick film deposits from other elements of these electronic devices such as conductive layers. A problem arises in some of these devices in that the solvent used in the thick film pastes, usually an ester or ether type solvent, is frequently aggressive to the polymer protective layer and may lead to short circuits. This can lead to problems on the surface of the substrate such as pealing or dissolution of the protective layer from the substrate when that layer is exposed to the thick film paste. An additional utility of such protective layers is the blocking of UV radiation so that the amount of radiation from the backside of the device reaching the thick film is reduced, thus increasing contrast between irradiated regions and regions protected by the protective layer in a self-aligned fabrication environment.
Wang et al in the Proceedings of the SPIE—The International Society for Optical Engineering (1999) vol. 3906, p. 619-24 describes the electrical characterization of polymer thick film resistors. Fukuda et al (U.S. Pat. No. 5,601,638) describes a thick film paste for use in the formation of circuit components. Ezaki (U.S. Pat. No. 5,362,927) reports a thick film hybrid circuit board device formed by lamination. Kazunori et al (JP 2001155626 A) provide a method for producing a display substrate. Takehiro and Shigeo (JP 10340666 A) describe a field emission element. Kazunori and Shinsuke ((JP 2001111217 A) provide a method of forming laminated wiring.